1. Field of the Invention
The present invention relates generally to a vibration damping rubber bushing adapted for installation between components to be linked in a vibration damped manner, and relates in particular to a vibration damping rubber bushing having anti-slip projections formed on the axial end faces of an inner cylindrical fitting.
2. Description of the Related Art
The use of vibration damping rubber bushings in systems such as automotive suspension mechanisms is widely known. A typical vibration damping rubber bushing of this kind has a main rubber elastic body bonded to the outer circumferential face of an inner cylindrical fitting of round cylindrical shape, and is installed with the inner cylindrical fitting attached to one component of the vibration damped linkage, and with the outer circumferential face of the main rubber elastic body attached to the other component of the vibration damped linkage.
In a known design for a vibration damping rubber bushing, anti-slip projections are formed on axial end faces of the inner cylindrical fitting in order to prevent relative rotation of the inner cylindrical fitting about its center with respect to one component of the vibration damped linkage while in the installed state. JP-A-2005-337473 discloses one such design, for example. This inner cylindrical fitting is secured in the axial direction by a fastening rod passed through the interior, and is installed with its axial end faces pushing against one component of the vibration damped linkage so that the anti-slip projections bite in and function as a rotation inhibiting mechanism.
However, when anti-slip projections are formed on the axial end faces of the inner cylindrical fitting, even with the fitting pushing against one component of the vibration damped linkage, gaps tend to form between the opposed faces of the component of the vibration damped linkage and the axial end face of the inner cylindrical fitting, between adjacent anti-slip projections. A resultant risk is that rain water can seep through these gaps and penetrate to the inside circumferential face of the inner cylindrical fitting, causing problems such as rust or corrosion.
In order to address this problem, JP-A-2005-337473 proposed a construction having sealing rubber packed between adjacent anti-slip projections at the axial end faces of the inner cylindrical fitting. However, this posed the risk of a rubber coat forming over the distal edges of the anti-slip projections during the process of covering the axial end faces of the inner cylindrical fitting with the seal rubber, and the presence of such a rubber coat may impair the rotation inhibiting function afforded by wedging in by the anti-slip projections. Another risk was that the sealing rubber may experience diminished sealing performance due to deterioration or damaged caused by ozone, ultraviolet light, rainwater, particles of sand, and the like.